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zfs: damage control racing .. lookups in face of mkdir/rmdir
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Authored by mjg on Apr 15 2021, 8:04 AM.

Details

Summary

See the added comment.

Note the patch does not address anything for stable/12 as it lacks the seqc infrastructure. Regardless of that, what needs to be done here is a revamp of the lookup primitive but I have no interest in working on it.

Test Plan

Trips over patched stress2 crossmp4 test.

Diff Detail

Repository
rG FreeBSD src repository
Lint
Automatic diff as part of commit; lint not applicable.
Unit
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

mjg requested review of this revision.Apr 15 2021, 8:04 AM

Panic was easily reproducible w/ (broken/modified) stress2 on arm64 and so far not reproducible with this change.

Is there anyone else familiar with the VFS stuff going on here who can help with this review? It's over my head at the moment.

kib added a subscriber: kib.

Not entering an entry into namecache is always fine.

This revision is now accepted and ready to land.Apr 21 2021, 2:28 PM